Regarding the OC, speaking for myself at least I must admit that my attention was first drawn to the piece by its reputation as both extremely long and extremely difficult, and I'm sure this is true of a lot of listeners. Still, according to an old edition of the Guinness Book, the longest piece ever performed at time of going to press consisted simply of every possible permutation of the notes in a one-octave ascending C major scale (it took many hours and multiple performers to reach "the best bit - the end"), which is surely an exercise in excruciating tedium for both performer(s) and listener (this, I suppose, would be an example of the sort of mindlessness that could be spun into a piece of absurd length which Mr. Hinton describes above - and given that each permutation is supposed to be different, one slip of a finger and you've screwed up the point of the piece, insofar as there is a point). And that the OC has captured more imaginations than mindless permutations of the C major scale would seem to bear witness to the fact that there is more to the piece than just its length and difficulty. Perhaps, though, the length and difficulty were Sorabji's way of discouraging the casual listener? I know he felt his pieces should only be performed by the very best, and I wouldn't be surprised if he also intended for them only to be heard by people who could truly appreciate them, irrespective of their length and difficulty.
But while there is clearly more to the OC than its length and difficulty which keeps people listening to it, it may perhaps be those sides of its reputation which draw some people to the piece - and to other works by Sorabji - in the first place. The length and difficulty draw them in, the music itself keeps them there (sometimes). A similar argument could perhaps be made for such composers as Alkan, Busoni, Godowsky, Reger.... their music has a reputation for being difficult for performers (and sometimes for listeners) that has kept them out of the spotlight, but those who have heard their works are very fond of them. (I must admit that's what sparked my interest in Alkan, but not Godowsky or Reger. And I'm not really a fan of Busoni.)
My own interest in the OC, though, remains low, as I've no idea how any of it sounds since neither Madge nor Ogdon's recordings have sound clips available. Perhaps when Dr. Powell feels ready to put the piece on disc and clips are made available for would-be listeners I'll re-evaluate my interest in it, but everything I've heard about the piece has made me think I'd get lost in its labyrinthine counterpoint very quickly. (And were Sorabji alive to be aware of this, he'd probably consider my reluctance a sign that I'm not worthy to hear it anyway.

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